1// -*- C++ -*-
2//===----------------------------------------------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef _LIBCPP_SYNCSTREAM
11#define _LIBCPP_SYNCSTREAM
12
13/*
14 syncstream synopsis
15
16#include <ostream> // see [ostream.syn]
17
18namespace std {
19 template<class charT, class traits, class Allocator>
20 class basic_syncbuf;
21
22 // [syncstream.syncbuf.special], specialized algorithms
23 template<class charT, class traits, class Allocator>
24 void swap(basic_syncbuf<charT, traits, Allocator>&,
25 basic_syncbuf<charT, traits, Allocator>&);
26
27 using syncbuf = basic_syncbuf<char>;
28 using wsyncbuf = basic_syncbuf<wchar_t>;
29
30 template<class charT, class traits, class Allocator>
31 class basic_osyncstream;
32
33 using osyncstream = basic_osyncstream<char>;
34 using wosyncstream = basic_osyncstream<wchar_t>;
35
36 template<class charT, class traits, class Allocator>
37 class basic_syncbuf : public basic_streambuf<charT, traits> {
38 public:
39 using char_type = charT;
40 using int_type = typename traits::int_type;
41 using pos_type = typename traits::pos_type;
42 using off_type = typename traits::off_type;
43 using traits_type = traits;
44 using allocator_type = Allocator;
45
46 using streambuf_type = basic_streambuf<charT, traits>;
47
48 // [syncstream.syncbuf.cons], construction and destruction
49 basic_syncbuf()
50 : basic_syncbuf(nullptr) {}
51 explicit basic_syncbuf(streambuf_type* obuf)
52 : basic_syncbuf(obuf, Allocator()) {}
53 basic_syncbuf(streambuf_type*, const Allocator&);
54 basic_syncbuf(basic_syncbuf&&);
55 ~basic_syncbuf();
56
57 // [syncstream.syncbuf.assign], assignment and swap
58 basic_syncbuf& operator=(basic_syncbuf&&);
59 void swap(basic_syncbuf&);
60
61 // [syncstream.syncbuf.members], member functions
62 bool emit();
63 streambuf_type* get_wrapped() const noexcept;
64 allocator_type get_allocator() const noexcept;
65 void set_emit_on_sync(bool) noexcept;
66
67 protected:
68 // [syncstream.syncbuf.virtuals], overridden virtual functions
69 int sync() override;
70
71 private:
72 streambuf_type* wrapped; // exposition only
73 bool emit_on_sync{}; // exposition only
74 };
75
76 // [syncstream.syncbuf.special], specialized algorithms
77 template<class charT, class traits, class Allocator>
78 void swap(basic_syncbuf<charT, traits, Allocator>&,
79 basic_syncbuf<charT, traits, Allocator>&);
80
81 template<class charT, class traits, class Allocator>
82 class basic_osyncstream : public basic_ostream<charT, traits> {
83 public:
84 using char_type = charT;
85 using int_type = typename traits::int_type;
86 using pos_type = typename traits::pos_type;
87 using off_type = typename traits::off_type;
88 using traits_type = traits;
89
90 using allocator_type = Allocator;
91 using streambuf_type = basic_streambuf<charT, traits>;
92 using syncbuf_type = basic_syncbuf<charT, traits, Allocator>;
93
94 // [syncstream.osyncstream.cons], construction and destruction
95 basic_osyncstream(streambuf_type*, const Allocator&);
96 explicit basic_osyncstream(streambuf_type* obuf)
97 : basic_osyncstream(obuf, Allocator()) {}
98 basic_osyncstream(basic_ostream<charT, traits>& os, const Allocator& allocator)
99 : basic_osyncstream(os.rdbuf(), allocator) {}
100 explicit basic_osyncstream(basic_ostream<charT, traits>& os)
101 : basic_osyncstream(os, Allocator()) {}
102 basic_osyncstream(basic_osyncstream&&) noexcept;
103 ~basic_osyncstream();
104
105 // [syncstream.osyncstream.assign], assignment
106 basic_osyncstream& operator=(basic_osyncstream&&);
107
108 // [syncstream.osyncstream.members], member functions
109 void emit();
110 streambuf_type* get_wrapped() const noexcept;
111 syncbuf_type* rdbuf() const noexcept { return const_cast<syncbuf_type*>(addressof(sb)); }
112
113 private:
114 syncbuf_type sb; // exposition only
115 };
116}
117
118*/
119
120#if __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
121# include <__cxx03/__config>
122#else
123# include <__config>
124
125// standard-mandated includes
126
127// [syncstream.syn]
128# include <ostream>
129
130# if _LIBCPP_HAS_LOCALIZATION
131
132# include <__mutex/lock_guard.h>
133# include <__utility/move.h>
134# include <ios>
135# include <iosfwd> // required for declaration of default arguments
136# include <streambuf>
137# include <string>
138# if _LIBCPP_HAS_THREADS
139# include <map>
140# include <shared_mutex>
141# endif
142
143# if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
144# pragma GCC system_header
145# endif
146
147_LIBCPP_PUSH_MACROS
148# include <__undef_macros>
149
150_LIBCPP_BEGIN_NAMESPACE_STD
151
152# if _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_EXPERIMENTAL_SYNCSTREAM
153
154// [syncstream.syncbuf.overview]/1
155// Class template basic_syncbuf stores character data written to it,
156// known as the associated output, into internal buffers allocated
157// using the object's allocator. The associated output is transferred
158// to the wrapped stream buffer object *wrapped when emit() is called
159// or when the basic_syncbuf object is destroyed. Such transfers are
160// atomic with respect to transfers by other basic_syncbuf objects
161// with the same wrapped stream buffer object.
162//
163// This helper singleton is used to implement the required
164// synchronisation guarantees.
165# if _LIBCPP_HAS_THREADS
166class __wrapped_streambuf_mutex {
167 _LIBCPP_HIDE_FROM_ABI __wrapped_streambuf_mutex() = default;
168
169public:
170 __wrapped_streambuf_mutex(const __wrapped_streambuf_mutex&) = delete;
171 __wrapped_streambuf_mutex& operator=(const __wrapped_streambuf_mutex&) = delete;
172
173 _LIBCPP_HIDE_FROM_ABI void __inc_reference([[maybe_unused]] void* __ptr) {
174 _LIBCPP_ASSERT_INTERNAL(__ptr != nullptr, "non-wrapped streambufs are never written to");
175 unique_lock __lock{__mutex_};
176 ++__lut_[reinterpret_cast<uintptr_t>(__ptr)].__count;
177 }
178
179 // pre: __ptr is in __lut_
180 _LIBCPP_HIDE_FROM_ABI void __dec_reference([[maybe_unused]] void* __ptr) noexcept {
181 unique_lock __lock{__mutex_};
182
183 auto __it = __get_it(__ptr);
184 if (__it->second.__count == 1)
185 __lut_.erase(__it);
186 else
187 --__it->second.__count;
188 }
189
190 // TODO
191 // This function causes emit() aquire two mutexes:
192 // - __mutex_ shared
193 // _ __get_it(__ptr)->second.__mutex exclusive
194 //
195 // Instead store a pointer to __get_it(__ptr)->second.__mutex when
196 // calling __inc_reference.
197 //
198 // pre: __ptr is in __lut_
199 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI lock_guard<mutex> __get_lock([[maybe_unused]] void* __ptr) noexcept {
200 shared_lock __lock{__mutex_};
201 return lock_guard{__get_it(__ptr)->second.__mutex};
202 }
203
204 // This function is used for testing.
205 //
206 // It is allowed to call this function with a non-registered pointer.
207 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI size_t __get_count([[maybe_unused]] void* __ptr) noexcept {
208 _LIBCPP_ASSERT_INTERNAL(__ptr != nullptr, "non-wrapped streambufs are never written to");
209 shared_lock __lock{__mutex_};
210
211 auto __it = __lut_.find(reinterpret_cast<uintptr_t>(__ptr));
212 return __it != __lut_.end() ? __it->second.__count : 0;
213 }
214
215 [[nodiscard]] static _LIBCPP_HIDE_FROM_ABI __wrapped_streambuf_mutex& __instance() noexcept {
216 static __wrapped_streambuf_mutex __result;
217 return __result;
218 }
219
220private:
221 struct __value {
222 mutex __mutex;
223 size_t __count{0};
224 };
225
226 shared_mutex __mutex_;
227 map<uintptr_t, __value> __lut_;
228
229 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI map<uintptr_t, __value>::iterator __get_it(void* __ptr) noexcept {
230 _LIBCPP_ASSERT_INTERNAL(__ptr != nullptr, "non-wrapped streambufs are never written to");
231
232 auto __it = __lut_.find(reinterpret_cast<uintptr_t>(__ptr));
233 _LIBCPP_ASSERT_INTERNAL(__it != __lut_.end(), "using a wrapped streambuf that has not been registered");
234 _LIBCPP_ASSERT_INTERNAL(__it->second.__count >= 1, "found an inactive streambuf wrapper");
235 return __it;
236 }
237};
238# endif // _LIBCPP_HAS_THREADS
239
240// basic_syncbuf
241
242// The class uses a basic_string<_CharT, _Traits, _Allocator> as
243// internal buffer. Per [syncstream.syncbuf.cons]/4
244// Remarks: A copy of allocator is used to allocate memory for
245// internal buffers holding the associated output.
246//
247// Therefore the allocator used in the constructor is passed to the
248// basic_string. The class does not keep a copy of this allocator.
249template <class _CharT, class _Traits, class _Allocator>
250class basic_syncbuf : public basic_streambuf<_CharT, _Traits> {
251public:
252 using char_type = _CharT;
253 using traits_type = _Traits;
254 using int_type = typename traits_type::int_type;
255 using pos_type = typename traits_type::pos_type;
256 using off_type = typename traits_type::off_type;
257 using allocator_type = _Allocator;
258
259 using streambuf_type = basic_streambuf<_CharT, _Traits>;
260
261 // [syncstream.syncbuf.cons], construction and destruction
262
263 _LIBCPP_HIDE_FROM_ABI basic_syncbuf() : basic_syncbuf(nullptr) {}
264
265 _LIBCPP_HIDE_FROM_ABI explicit basic_syncbuf(streambuf_type* __obuf) : basic_syncbuf(__obuf, _Allocator()) {}
266
267 _LIBCPP_HIDE_FROM_ABI basic_syncbuf(streambuf_type* __obuf, _Allocator const& __alloc)
268 : __wrapped_(__obuf), __str_(__alloc) {
269 __inc_reference();
270 }
271
272 _LIBCPP_HIDE_FROM_ABI basic_syncbuf(basic_syncbuf&& __other)
273 : __wrapped_(__other.get_wrapped()), __str_(std::move(__other.__str_)), __emit_on_sync_(__other.__emit_on_sync_) {
274 __move_common(__other);
275 }
276
277 _LIBCPP_HIDE_FROM_ABI ~basic_syncbuf() {
278# if _LIBCPP_HAS_EXCEPTIONS
279 try {
280# endif // _LIBCPP_HAS_EXCEPTIONS
281 emit();
282# if _LIBCPP_HAS_EXCEPTIONS
283 } catch (...) {
284 }
285# endif // _LIBCPP_HAS_EXCEPTIONS
286 __dec_reference();
287 }
288
289 // [syncstream.syncbuf.assign], assignment and swap
290
291 _LIBCPP_HIDE_FROM_ABI basic_syncbuf& operator=(basic_syncbuf&& __other) {
292 // The function is specified to call emit. This call should
293 // propagate the exception thrown.
294 emit();
295 __dec_reference();
296
297 __wrapped_ = __other.get_wrapped();
298 __str_ = std::move(__other.__str_);
299 __emit_on_sync_ = __other.__emit_on_sync_;
300
301 __move_common(__other);
302
303 return *this;
304 }
305
306 _LIBCPP_HIDE_FROM_ABI void swap(basic_syncbuf& __other) {
307 _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(
308 allocator_traits<_Allocator>::propagate_on_container_swap::value || get_allocator() == __other.get_allocator(),
309 "violates the mandated swap precondition");
310
311 basic_syncbuf __tmp(std::move(__other));
312 __other = std::move(*this);
313 *this = std::move(__tmp);
314 }
315
316 // [syncstream.syncbuf.members], member functions
317
318 _LIBCPP_HIDE_FROM_ABI bool emit() { return emit(false); }
319
320 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI streambuf_type* get_wrapped() const noexcept { return __wrapped_; }
321
322 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI allocator_type get_allocator() const noexcept { return __str_.get_allocator(); }
323
324 _LIBCPP_HIDE_FROM_ABI void set_emit_on_sync(bool __b) noexcept { __emit_on_sync_ = __b; }
325
326protected:
327 // [syncstream.syncbuf.virtuals], overridden virtual functions
328
329 _LIBCPP_HIDE_FROM_ABI_VIRTUAL
330 int sync() override {
331 if (__emit_on_sync_ && !emit(true))
332 return -1;
333 return 0;
334 }
335
336 _LIBCPP_HIDE_FROM_ABI_VIRTUAL
337 int_type overflow(int_type __c = traits_type::eof()) override {
338 if (traits_type::eq_int_type(__c, traits_type::eof()))
339 return traits_type::not_eof(__c);
340
341 if (this->pptr() == this->epptr()) {
342# if _LIBCPP_HAS_EXCEPTIONS
343 try {
344# endif
345 size_t __size = __str_.size();
346 __str_.resize(__str_.capacity() + 1);
347 _LIBCPP_ASSERT_INTERNAL(__str_.size() > __size, "the buffer hasn't grown");
348
349 char_type* __p = static_cast<char_type*>(__str_.data());
350 this->setp(__p, __p + __str_.size());
351 this->pbump(__size);
352
353# if _LIBCPP_HAS_EXCEPTIONS
354 } catch (...) {
355 return traits_type::eof();
356 }
357# endif
358 }
359
360 return this->sputc(traits_type::to_char_type(__c));
361 }
362
363private:
364 streambuf_type* __wrapped_;
365
366 // TODO Use a more generic buffer.
367 // That buffer should be light with almost no additional headers. Then
368 // it can be use here, the __retarget_buffer, and place that use
369 // the now removed get_temporary_buffer
370
371 basic_string<_CharT, _Traits, _Allocator> __str_;
372 bool __emit_on_sync_{false};
373
374 _LIBCPP_HIDE_FROM_ABI bool emit(bool __flush) {
375 if (!__wrapped_)
376 return false;
377
378# if _LIBCPP_HAS_THREADS
379 lock_guard<mutex> __lock = __wrapped_streambuf_mutex::__instance().__get_lock(__wrapped_);
380# endif
381
382 bool __result = true;
383 if (this->pptr() != this->pbase()) {
384 _LIBCPP_ASSERT_INTERNAL(this->pbase() && this->pptr() && this->epptr(), "all put area pointers shold be valid");
385
386 // The __str_ does not know how much of its buffer is used. This
387 // information is extracted from the information of the base class.
388 __result &= (__wrapped_->sputn(this->pbase(), this->pptr() - this->pbase()) != -1);
389 // Clears the buffer, but keeps the contents (and) size of the
390 // internal buffer.
391 this->setp(this->pbase(), this->epptr());
392 }
393
394 if (__flush)
395 __result &= (__wrapped_->pubsync() != -1);
396
397 return __result;
398 }
399
400 _LIBCPP_HIDE_FROM_ABI void __move_common(basic_syncbuf& __other) {
401 // Adjust the put area pointers to our buffer.
402 char_type* __p = static_cast<char_type*>(__str_.data());
403 this->setp(__p, __p + __str_.size());
404 this->pbump(__other.pptr() - __other.pbase());
405
406 // Clear __other_ so the destructor will act as a NOP.
407 __other.setp(nullptr, nullptr);
408 __other.__wrapped_ = nullptr;
409 }
410
411 _LIBCPP_HIDE_FROM_ABI void __inc_reference() {
412# if _LIBCPP_HAS_THREADS
413 if (__wrapped_)
414 __wrapped_streambuf_mutex::__instance().__inc_reference(__wrapped_);
415# endif
416 }
417
418 _LIBCPP_HIDE_FROM_ABI void __dec_reference() noexcept {
419# if _LIBCPP_HAS_THREADS
420 if (__wrapped_)
421 __wrapped_streambuf_mutex::__instance().__dec_reference(__wrapped_);
422# endif
423 }
424};
425
426using std::syncbuf;
427# if _LIBCPP_HAS_WIDE_CHARACTERS
428using std::wsyncbuf;
429# endif
430
431// [syncstream.syncbuf.special], specialized algorithms
432template <class _CharT, class _Traits, class _Allocator>
433_LIBCPP_HIDE_FROM_ABI void
434swap(basic_syncbuf<_CharT, _Traits, _Allocator>& __lhs, basic_syncbuf<_CharT, _Traits, _Allocator>& __rhs) {
435 __lhs.swap(__rhs);
436}
437
438// basic_osyncstream
439
440template <class _CharT, class _Traits, class _Allocator>
441class basic_osyncstream : public basic_ostream<_CharT, _Traits> {
442public:
443 using char_type = _CharT;
444 using traits_type = _Traits;
445 using int_type = typename traits_type::int_type;
446 using pos_type = typename traits_type::pos_type;
447 using off_type = typename traits_type::off_type;
448
449 using allocator_type = _Allocator;
450 using streambuf_type = basic_streambuf<char_type, traits_type>;
451 using syncbuf_type = basic_syncbuf<char_type, traits_type, allocator_type>;
452
453 // [syncstream.osyncstream.cons], construction and destruction
454
455 _LIBCPP_HIDE_FROM_ABI basic_osyncstream(streambuf_type* __obuf, allocator_type const& __alloc)
456 : basic_ostream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(__obuf, __alloc) {}
457
458 _LIBCPP_HIDE_FROM_ABI explicit basic_osyncstream(streambuf_type* __obuf)
459 : basic_osyncstream(__obuf, allocator_type()) {}
460
461 _LIBCPP_HIDE_FROM_ABI basic_osyncstream(basic_ostream<char_type, traits_type>& __os, allocator_type const& __alloc)
462 : basic_osyncstream(__os.rdbuf(), __alloc) {}
463
464 _LIBCPP_HIDE_FROM_ABI explicit basic_osyncstream(basic_ostream<char_type, traits_type>& __os)
465 : basic_osyncstream(__os, allocator_type()) {}
466
467 _LIBCPP_HIDE_FROM_ABI basic_osyncstream(basic_osyncstream&& __other) noexcept
468 : basic_ostream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(std::move(__other.__sb_)) {
469 this->set_rdbuf(std::addressof(__sb_));
470 }
471
472 // [syncstream.osyncstream.assign], assignment
473
474 _LIBCPP_HIDE_FROM_ABI basic_osyncstream& operator=(basic_osyncstream&& __other) = default;
475
476 // [syncstream.osyncstream.members], member functions
477
478 _LIBCPP_HIDE_FROM_ABI void emit() {
479 // The basic_ostream::put places the sentry in a try
480 // catch, this does not match the wording of the standard
481 // [ostream.unformatted]
482 // TODO validate other unformatted output functions.
483 typename basic_ostream<char_type, traits_type>::sentry __s(*this);
484 if (__s) {
485# if _LIBCPP_HAS_EXCEPTIONS
486 try {
487# endif
488
489 if (__sb_.emit() == false)
490 this->setstate(ios::badbit);
491# if _LIBCPP_HAS_EXCEPTIONS
492 } catch (...) {
493 this->__set_badbit_and_consider_rethrow();
494 }
495# endif
496 }
497 }
498
499 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI streambuf_type* get_wrapped() const noexcept { return __sb_.get_wrapped(); }
500
501 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI syncbuf_type* rdbuf() const noexcept {
502 return const_cast<syncbuf_type*>(std::addressof(__sb_));
503 }
504
505private:
506 syncbuf_type __sb_;
507};
508
509using std::osyncstream;
510# if _LIBCPP_HAS_WIDE_CHARACTERS
511using std::wosyncstream;
512# endif
513
514# endif // _LIBCPP_STD_VER >= 20 && _LIBCPP_HAS_EXPERIMENTAL_SYNCSTREAM
515
516_LIBCPP_END_NAMESPACE_STD
517
518_LIBCPP_POP_MACROS
519
520# endif // _LIBCPP_HAS_LOCALIZATION
521#endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
522
523#endif // _LIBCPP_SYNCSTREAM